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How to change calibration in a rostock max?

Posted: Mon Feb 16, 2015 9:44 pm
by Lasivian
My printer constantly has printed things 5% undersized and i'm not sure how to fix this (or even if it's worth the effort)

Thanks!

Re: How to change calibration in a rostock max?

Posted: Tue Feb 17, 2015 4:00 am
by teoman
Is it %5 in all directions? (XYZ) or just or just one?

What material? Abs? Pla?

There is a scale option that you can set which will make the object %5 larger.

Re: How to change calibration in a rostock max?

Posted: Tue Feb 17, 2015 9:27 am
by geneb
Here's a simple way to adjust the dimensions of a print (taken from here: http://minow.blogspot.com/)

1. Print a calibration object that's 100mm long, by 2mm high and 2mm wide.

2. Measure the length of the object. If it's wrong, you need to adjust the DELTA_DIAGONAL_ROD length in the firmware.

3. The new DELTA_DIAGONAL_ROD is calculated like this:
new value = measured_length / 100 * original DELTA_DIAGONAL_ROD

The website has the division reversed, but I've found that I get better results with it as I've written it.

g.

Re: How to change calibration in a rostock max?

Posted: Tue Feb 17, 2015 11:52 am
by JFettig
Gene,

I've been struggling a little bit with this to get it dialed in, my expectations are probably a bit high though. I've followed that blog carefully, and I'm actually doing it again right now.

It seems like the left side of my part is closer to dimension in the y-axis than the right side, kinda odd.

My calibration object has a 4x100mm strip, 4mm tall(get it way from the base plate) but its actually stepped, so it has 4mmx80, 4mmx60, 4mmx40, 4mmx20 all on it on center

Smaller dims seem to be large, larger dims are small, 20mm in the x-axis is 20.09mm, 40mm is 39.82, 60mm is 59.66, 80mm at 79.47, 100mm at 99.21, this is with 269mm rod length

I averaged all the differences and came up with 268.5mm new rod length, printed the cal object again and averaged and came up with 268.17mm, now I'm printing again to see what I come up with.

I won't scale my steps/mm because that will also effect Z, which is dead on.

See attached files.

Re: How to change calibration in a rostock max?

Posted: Tue Feb 17, 2015 2:59 pm
by bot
Simplify3D has a parameter for shrinking or growing just the perimeter of an object in the x/y direction. It leaves the Z alone. I haven't used it yet, but I will soon and I'm hoping it is awesome.

Re: How to change calibration in a rostock max?

Posted: Tue Feb 17, 2015 3:23 pm
by JFettig
It would be nice if the issue was constant but if a part that is 20mm wide is too big and a part that is 100mm wide is way too small, it won't help much.

Re: How to change calibration in a rostock max?

Posted: Tue Feb 17, 2015 4:25 pm
by geneb
That is truly bizarre. BTW, NEVER change the movement steps per MM. That should be treated as a constant - if tweaking it fixes something then it's masking a different problem. :)

You might want to pop the belts off and check to make sure that each Cheapskate is properly adjusted. One getting a bit grabby might cause an issue. Not sure though - I've not experienced what you're going through. :(

g.

Re: How to change calibration in a rostock max?

Posted: Tue Feb 17, 2015 5:48 pm
by JFettig
Yeah, I design machines for a living, tweaking steps/mm is not something I'd consider!

I checked the cheapskates, they're solid, everything moves great. Recently re-squared the towers as they started to come loose.